The generating sets implement combustion engines supplied by an air/fuel mixture, with the air being taken by the intake duct of a turbocharger. This intake duct is provided with an air filter.
In the category of high-power generating sets, the following in particular can be distinguished:                the sets referred to as “heavy-duty”, which are used continuously, generally outdoors, likely to be used in dusty and/or wet environments;        the sets referred to as “stand-by”, which are by default on standby, and triggered in the event of an emergency; these sets are conventionally used in hospital environments and are stored in technical premises.        
The air filters of the “heavy duty” sets require to be protected from their environment.
For this, the set generally has a case intended to receive the air filter.
In reference to FIG. 8, the mounting of such a filter implies a succession of operations rendering the mounting time relatively high.
The case such as shown in FIG. 8 comprises in particular a cover 81 which, once removed, makes it possible to extract or install a filter.
Note that this technique involves the inserting of the filter in the case according to the longitudinal axis of the latter.
Yet, a case conventionally has a length of 70 cm, with this length being approximately that of the filter. It is therefore necessary to have a space that is twice the length L: once for the encumbrance of the case, and once for the presentation of the filter in front the case during the installation of the filter in the case.
In certain cases, this operation is rendered tedious and even impossible, due to the presence of obstacles (such as equipment and/or portions of structures) in the immediate vicinity of the generating set.
Another technique has been proposed by prior art, according to which the case is moulded on the plates of the filter, formant with the latter a one-piece unit.
The mounting of the case/filter unit is considerably simplified, the outlet duct of the filter being intended to be press fitted directly to the duct of the compressor of the set.
However, the disadvantage of this technique is that the case and the filter cannot be separated. Consequently, each filter change tends to generate a quantity of waste that is greater than the replacing of the filter alone.
In addition, the one-piece case/filter unit is a relatively expensive part.
According to yet another technique proposed by prior art, the filter is mounted in a case constituted of two portions articulated in relation to one another. According to this technique, the filter is installed in one of the portions of the case, with the other portion folded down on the first in order to close the case. A ring equipped with ramps present at the bottom of the case is then actuated in order to cause a longitudinal locking of the filter in the case and bring the seal of the upper plate of the filter into compressed position against the case. Note that the locking and the sealing of the filter in the case are as such obtained using a specific part, which tends to increase the complexity of the unit as well as its cost of manufacture.
Moreover, the case has a sleeve intended to be press fitted to the equipment. It is therefore understood that the case exerts a support function of the filter on the equipment, as the filter is not mechanically in cooperation with the air intake of the equipment.
A consequence is that according to this technique, it is not provided to mount the filter without the case (the latter forming a means of linking between the filter and the equipment).
In parallel, for the “standby” sets, it is conventional to implement the free air filters, i.e. without case.
The filter is press fitted to the duct of the compressor of the set and, where applicable, a square removably attached to the frame of the set maintains the filter at its end opposite the press fitting by exerting a bearing on the rear plate of the filter.
The mounting of the filter according to this technique is particularly simple and rapid.
However, this technique is not adapted to exterior applications or to very dusty environments, as no protection of the filter is provided.
Yet, the manufacturers of generating sets want to propose or have modular solutions, combining the simplicity of mounting of the filter according to the “standby” technique with the possibility of protecting the filter in the event of exterior use.